This application relates to the delivery of sterilant from a cassette to an instrument sterilizer, and more particularly to the extraction of sterilant from the cassette.
One popular method for sterilizing instruments, such as medical devices, is to contact the devices with a vapor phase chemical sterilant, such as hydrogen peroxide. In many such sterilizers, it is preferred to deliver the sterilant in liquid form and vaporize it in the sterilizer. One particularly convenient and accurate method for delivering the liquid sterilant is to put a predetermined quantity of sterilant into a cassette and deliver the cassette to the sterilizer. The sterilizer then automatically extracts the sterilant from the cassette and uses it for sterilization procedure. Typically, such a cassette would entail multiple cells containing equal amounts of liquid sterilant with a sterilization procedure employing the sterilant from one or more cells. Such a system is currently available in the STERRAD® sterilization system available from Advanced Sterilization Products in Irvine, Calif.
U.S. Pat. Nos. 4,817,800; 4,869,286; 4,899,519; 4,909,287; 4,913,196; 4,938,262; 4,941,518; 5,882,611; 5,887,716; and 6,412,340, each incorporated herein by reference, disclose such cassettes and a method for draining liquid sterilant from a cell within a cassette. In essence, the cassette travels horizontally with a horizontally oriented cell and one or more needles pierces the cell from below while compressed air is applied to an upper surface of the cassette cell. The cell is made from a flexible material so that the air compresses the cell and forces the sterilant out through the needles. Such a system limits the cassette design to an outer shell providing rigidity enclosing an inner cell of a flexible material. Further, the cell needs to be designed carefully to allow a complete collapse without trapping any of the liquid sterilant within a wrinkle in the cell during its collapse.
The present invention overcomes these and other limitations of the prior art.